Question

A person supports a book between his finger and thumb as shown (the point of grip is assumed to be at the
corner of the book). If the book has a weight of W then the person is producing a torque on the book of
(A)Wa/2 anticlockwise
(B) Wb/2 anticlockwise
(C) Wa anticlockwise
(D) Wa clockwise
Answer is B...... Kindly explain this...... ​

Answer 1

If the book has a weight of W then the person is producing a torque of Wb/2 anticlockwise.

Torque produced due to the weight of the book is = Wb/2

A person supports a book between his finger and thumb, so for this condition torque can be balanced only if the torque applied by the boy is equal in magnitude and opposite in direction.

So the torque applied by the person should be in anticlockwise direction and magnitude of the torque will be Wb/2.

Refer to the attached figure for more details.